1. Field of the Invention
The present invention relates to a lip member for use in an opening of a housing for a small pet animal such as a rodent, e.g., a hamster or the like, and to a housing system.
2. Description of the Related Art
Recently, hamsters have become popular small pet animals especially for city dwellers since hamsters have a nice appearance and good behavior and are easy to keep even in a relatively small house such as an apartment house, a town house, and the like.
Some conventional housings for breeding and observing hamsters have a structure for connecting an additional passage tube.
For example, a plastic molded housing having an opening formed on a side wall thereof for directly connecting a passage tube, or a housing having an opening formed on a side wall thereof with a lip member fitted around the opening for connecting a passage tube, have been provided.
However, since rodents such as hamsters, or the like, have a gnawing habit, a peripheral portion of an opening or a lip member attached around the opening, may be gnawed breaking the peripheral portion or the lip member. When such a peripheral portion of the opening or the lip member is gnawed, an additional passage tube can not be connected thereto. Further, hamsters may escape through the gnawed portion.
Additionally, in a housing having an opening formed on a side wall thereof for directly connecting a passage tube, the housing requires an integral structure for connecting the passage tube at a periphery of the opening, which complicates the structure of the housing. This also complicates a mold for manufacturing the housing, resulting in a high manufacturing cost.
On the other hand, in a housing having an opening formed on a side wall thereof with a lip member fitted around the opening for connecting a passage tube, if the lip member is made of metal, for example, it is possible to prevent the lip member, or a periphery of the opening, from being gnawed. However, such a metal lip member is more difficult to form than in a plastic lip member, and therefore the production cost will be increased.